(VIRGINIA BEACH, Va.) — The officers who confronted an alleged gunman during a mass shooting in a packed Virginia Beach municipal building helped prevent even more bloodshed.Twelve people were shot to death and four others were injured in Friday’s rampage, allegedly carried out by a disgruntled employee.But officials praised the responding officers who engaged the alleged shooter, DeWayne Craddock, 40, in a “long-term, large gunfight.””It is the most emotional event that one can ever go through,” said Virginia Beach Police Chief James Cevera at a news conference Saturday morning.”While we train extensively, while we go over all our protocols extensively, once you enter an environment such as this, everything changes,” he added. “Things change at a moment’s notice.”Police say Craddock entered Building 2 in the Municipal Center about 4 p.m. Friday and began shooting people “indiscriminately.” City manager Dave Hansen said Craddock, an engineer with the city for 15 years, was able to enter the public building with a security pass.At the time of the shooting, there were about 400 people in the three-story building, officials said.Once inside, Craddock, armed with a handgun and long gun, went to different floors looking for victims, police said.”Once he engaged in this activity, it just continued throughout the building,” Cevera said.Officers responded within minutes, Cevera said, and exchanged gunfire with Craddock.”Once they identified him and he identified them, he immediately opened fire,” the chief said of Craddock. “We immediately returned the fire.”The gunfight — which Cevera described as a “long-running gun battle” — lasted just under 30 minutes, the chief said.”This is not what is traditionally a police-involved shooting,” he added. “This was a long-term, large gunfight.”One of the officers was shot, but was saved by his bullet-proof vest, officials said.Before officers shot Craddock to death, he allegedly had killed 11 city workers and a city contractor, and wounded four others. The responding emergency teams were faced with a “horrific crime scene,” Cevera said.”This is a large scale crime scene,” he said Saturday. “It takes not only a physical, emotional and psychological toll on everyone who spent the night in that building.”I can’t speak enough about the courage of police and forensics are showing in that building with the carnage that exists there,” he said. “They are performing admirably.”The responding officers handled the crime scene with “compassion,” Cevera said.”Caring, assisting our brothers and sisters who worked for our city,” he said.City manager Dave Hansen said honor guard officers from the city’s police and fire departments would work as family liaisons with the victims’ families.”We’re going to wrap our arms around families,” he said Saturday.The shooting could have been worse, Cevera added, had it not been for the officers’ quick response.”Officers had to make instantaneous decisions,” the chief said of his crew. “They did it miraculously because … they did save other lives.”Copyright © 2019, ABC Radio. All rights reserved.